For many years, there has been an industry desire to develop products that provide effective lubrication of fibers. These fibers include hair and a variety of textile fibers including cotton, rayon, nylon, and polyester. The need for an effective lubricant has grown recently with the popularity of microfibers, a very low denier fiber. The smaller the fiber, the greater the need for lubrication to prevent breakage during processing. As will become clear, the ability to provide effective lubrication was limited first by the chemistry of the lubrication compounds and then by the limitations of formulating these compounds into compositions.
By lubrication and conditioning, we mean the alteration of the fiber surface to provide a softer more appealing feel to the touch and at the same time provide lower friction values when the fibers pass over each other or when they pass over other objects, like metal parts or combs. In general, lubrication is the alteration of the surface to effect these changes. Conditioning is a type of lubrication in which the aesthetics of the lubricant are appealing. Hair is conditioned, fibers are generally lubricated, but both are related concepts.
Very early products aimed at lubricating and conditioning of fibers were simply oil or silicone emulsions. These composition included an oil phase (hydrocarbon, triglyceride or silicone oil), one of more emulsifiers and water. The difficulty with this approach was two fold. The first was that emulsions are metastable materials, and given enough time will separate. In addition, these emulsions are very sensitive to addition of additional surface active materials since the addition would alter the surfactant balance of the original emulsion and lead to splitting of the emulsion. That splitting would manifest itself by the formation of a water phase and an oil phase from a product that was homogeneous milk like liquid. This inability to add other ingredients limits the use of such products.
More recently, there has been a desire to make a soluble molecule that contains both silicone soluble groups and water soluble groups. These products are called silicone glycols. The products overcame the limitations related to emulsification, but in order to obtain a suitable level of water solubility, the lubrication and conditioning properties were significantly lessened. The compromised conditioning and lubrication properties, their inability to provide emulsification properties and their high cost limited the usefulness of such materials.
Several attempts were made to combine in one molecule water soluble groups, silicone soluble groups and oil soluble groups to make a truly functional lubricant for use in aqueous systems. One class of compounds are the silicone esters. Silicone esters have been known for years. U.S. Pat. No. 4,724,248 issued February 1988 to Dexter et al is the first patent to disclose silicone fatty esters, primarily for use in electrical systems. O'Lenick et al in U.S. Pat. No. 5,136,063 issued Aug. 4, 1992 later expanded the field. Still later, these materials were modified using specific triglycerides to maintain properties of the oil. These include U.S. Pat. No. 6,646,144 to Klein discloses cranberry based silicone esters and U.S. Pat. No. 6,630,180 to Klein discloses raspberry silicone esters.
While functional as skin care materials, these materials do not have the necessary properties to make a truly functional highly efficacious conditioner/lubricant. In fact, the recent approaches listed above indicate the desirability of making a compound that will provide the necessary functionality, rather than a specifically targeted composition. In other words, the recent trends in the art teach away from the use compositions.
Providing conditioning and lubrication to fiber is a complicated process, particularly when it is attempted with one compound. The process of conditioning or lubricating the fiber from aqueous solution includes several often-competitive processes including wetting of the fiber, and the deposition of the lubricant or conditioner onto the fiber. For example if one uses the silicone esters disclosed in U.S. Pat. No. 5,136,063, the specific ester chosen must have (a) water solubility, (b) wetting properties to allow for the uniform distribution of the molecule on the fiber, (c) ability to deposit rather than to wash off and (d) outstanding conditioning effects. Unfortunately, the selection of a molecule that has all properties has been elusive. This is because the optimization of one property is achieved at the expense of another. If one wants to improve water solubility one can add a lager water soluble group. This would decrease wetting, minimize deposition, increase wash off and lower conditioning effectiveness.
In order to attempt to overcome these problems, we looked at making compositions, containing one silicone molecule and an added surface active agent. The concept was to make a composition that would allow various processes to go on simultaneously, with minimal interferences one to the other. Many approaches simply did not work due to interactions between the compounds and interferences in the various processes.